This invention relates to the use of a class of imidazoquinoxalines as fungicides. Some of the compounds useful in this invention are known in the art. Schipper and Day describe imidazoquinoxalines in J. Am. Chem. Soc. 73, 5672 (1951). However, no recognition of the fungicidal activity of these compounds has been made heretofore. Fungicidal compounds having fused ring structures are known. U.S. Pat. Nos. 2,933,502; 3,541,213 and 3,657,443 teach use of benzimidazole derivatives as fungicides. U.S. Pat. No. 3,091,613 teaches the use of 6-methyl-2,3-quinoxalinedithiolcyclic-S,S-dithiocarbonate as a fungicide. These references do not suggest any fungicidal activity for the imidazoquinoxalines of this invention.